1. Field
The present invention relates to enclosure-less fiber optic terminals.
2. Background
A fiber distribution terminal (FDT) is used to interconnect multiple fibers, typically originating from a common point, and distribute them to multiple different locations with output fiber cables. Typically, the connections are made between a larger multi-fiber bundle input cable and individual output fiber cables. An FDT is typically used in buildings such as multi-unit residences or commercial/office buildings. There could be a single FDT per building or perhaps one or more per floor or any combination in between depending on the fiber connection needs and capacity of the building.
One recurring issue faced when dealing with the installation of FDTs is how much input fiber cable is required to connect the FDT to some common point, which is often outdoors where the connections to the larger fiber networks (e.g., a city wide fiber network) are made. The common point could also be within the same building, perhaps on another floor or in the basement of the building. No matter the location of the common point, it is often necessary to physically locate the FDT before the required length of fiber cable between the FDT and the common point is known. This presents two problems. First, one must approximate and prepare a length of the input fiber cable before installing the FDT. If the approximated length is too short, the connection to the FDT cannot be made without a fiber cable splice and another length of input fiber cable. Conversely, if the approximated length is too long, then the excess slack of the fiber cable must be stored somewhere along the length of fiber cable, potentially introducing unwanted bends and thus unwanted bend loss into the fiber cable path. Second, it might be necessary to relocate the FDT so that the chosen or available fiber cable length is approximately correct, which could mean placing the FDT in an undesirable location. Accordingly there is a need to safely store excess fiber cable after installation and to feed fiber cable from an installed FDT. There is also a need for a convenient way to store the input fiber cable prior to installation of the FDT.
Affixing the FDT to its permanent location before connecting the input fiber cable to the common point would be convenient. Prior FDTs that include an external spool of fiber cable do not allow the FDT to be affixed to its permanent location because the enclosure of the FDT must rotate with the external spool of fiber cable. This configuration also prevents the installer from making the input fiber connections to the adapter pack prior to connecting the input fiber cable.
In some FDTs, input and output fiber cables enter and exit the FDT in only one direction. This configuration requires that the cables always be routed in the same direction. This configuration often makes the external installation difficult and the routing of cables to and from the FDT cumbersome. This situation can occur when the fiber must be routed to a higher floor, but the fiber output cables are downwardly aligned, meaning that the fiber cables must make a 180 degree turn after leaving the FDT. This often results, especially with less experienced installers, in damage to the fiber cable, due to inadvertent bend loss.
It is also important to protect the fiber cables as they are routed within the FDT. Typical FDTs contain connection blocks where the fibers of the larger input cable are individually matched to single output cables. Both the input and output cables are separately routed through the enclosure, with the installer having the responsibility of routing the fiber cables in such a way so as to avoid bends in the cable and thus bend loss. Installers, who may or may not be conscious of this responsibility, might not always appreciate the impact of their craftsmanship. Routing secured by cable ties or other more industrial type retaining clips could easily create inadvertent bends in the fiber cables, thus causing undesired loss of signal strength in the fiber cables. Therefore, it is desirable to have an FDT that conveniently stores fiber cable prior to installation and houses excess fiber cable after the input cable connection has been made. It is also desirable for the FDT to house the input fiber cable to output fiber cable connections and safely route the cables within the FDT to avoid bend loss while allowing the input and output fiber cables to enter/exit from multiple sides of the FDT.